Is it kaput??

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Mercedesstar

Active Member
Joined
May 1, 2012
Messages
105
Car
S320Cdi
Hi all
My engine, in a 1999 E320CDI, has over some time developed a metallic clacking noise, is the only way I can describe it. It is getting worse, and the engine has startet to idle rough as well, jumpy and rough. I hoped it had to do with the engine mounts, or certainly the clacking noise. But having changed the engine and gearbox mounts it seems to have got worse. It is only there during mild acceleration, accelerate slightly harder and the clacking goes away. It does not affect the performance of the engine, it runs perfectly otherwise, it starts on the button, oil is fine and fuel consumption is normal. The clacking noise and jumpy idle is only there when the engine gets warm. But at its worse it really does sound bad, clacking metallic noise is the only way to describe it. I left the engine running when I came home this afternoon and lifted the bonnet, trying to rev the engine from the engine bay does not give the clacking noise, so only under load. Gearbox is smooth, changes fine. When I lifted the bonnet the engine was visibly running jumpy.
It has got full service historie, had a new speed sensor last year with the service, I change oil between services, so every 3-5000 miles. It has got 135000 miles on it.
Any suggestions.
Thank you in advance
 
Sounds like a dribbling injector.

Try a strong dose of injector cleaner.
 
I hope it is and you are right. To me it sounds more like bottom end falling out. Away at the moment in wifes car, will let you know how I get on next week.
 
Hi all
My engine, in a 1999 E320CDI, has over some time developed a metallic clacking noise, is the only way I can describe it. It is getting worse, and the engine has startet to idle rough as well, jumpy and rough. I hoped it had to do with the engine mounts, or certainly the clacking noise. But having changed the engine and gearbox mounts it seems to have got worse. It is only there during mild acceleration, accelerate slightly harder and the clacking goes away. It does not affect the performance of the engine, it runs perfectly otherwise, it starts on the button, oil is fine and fuel consumption is normal. The clacking noise and jumpy idle is only there when the engine gets warm. But at its worse it really does sound bad, clacking metallic noise is the only way to describe it. I left the engine running when I came home this afternoon and lifted the bonnet, trying to rev the engine from the engine bay does not give the clacking noise, so only under load. Gearbox is smooth, changes fine. When I lifted the bonnet the engine was visibly running jumpy.
It has got full service historie, had a new speed sensor last year with the service, I change oil between services, so every 3-5000 miles. It has got 135000 miles on it.
Any suggestions.
Thank you in advance
135000 its only just run in! ive same car 207000 miles..
 
How could I ever doubt you, Dieselman. I wish I`d had a big nappy on when I heard the noise first time, I really thought it was something terminal, as I suppose it would to the untrained ear.
I have had previous good experiences with Lucas injector cleaner, Lucas Oil Products (UK) - Heavy Duty & High Performance Lubricants, so I have used some of that, and although not having got rid of the noise completely, it has reduced it and I will continue to put some Lucas in every tank. I will have it checked out by a previous Mercedes mechanic next Thursday and go from there.
Thanks
 
I change oil between services, so every 3-5000 miles.

Glad you got the problem sorted ... Thanks to the advice of DM.

Regarding the extra oil changes ..... If you use a good quality engine oil to the correct MB spec, it really does not need this.

I change the engine oil and filter every 10,000 miles on the E300TD.
It's now on 219,000 miles and it will run for ever.
;)
 
I wish I`d had a big nappy on when I heard the noise first time, I really thought it was something terminal,

The loud crack noise is pre-ignition detonation, which then travels through the hollow engine casing and literally sounds like the engine is splitting.
 
Update.
Had it put on Star, injector 3 is kaput. It shows 5.1, apparently it doesn`t get any worse than that, and injector 5 shows -4.9. I was told it was due to injector 5 trying to compensate for injector 3. He is changing injector 3 next Weds/Thurs, £120 for the injector and 1hr to change and do what is needed. Fingers crossed that it is only the one, apparently once one is changed others can decide to give up the ghost. Also that it comes out easily. The longest he has spent on getting an injector out is a day!!!
 
Update
Had injector 3 changed no problems, it came out fairly easy and the car is now running so much better. The mechanic was unfortunately right, injector 6 is now showing 4.4 and it can be heard just slightly when driving along. Whilst I was told these numbers, 5.1 and 4.4 by the mechanic, I dont actually know what they mean!! Mayby you, Dieselman, can help me out on this one? On top of this none of the glowplugs are working. But I expected that and has been putting it off for some time. Otherwise everything else is working fine on the old girl.
 

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